Nearly half of the forecast 610,000ML savings will come from washing machines, about 25 percent from showers and 22 percent from toilets. Environment Minister Ian Campbell said that mandatory water effiency labeling and standards scheme was the first kind in the world.

"By choosing more efficient appliances, the community could also save more than $600 million through reduced water and energy bills by 2021," he said. By late next year six appliances must carry water efficiency labels: washing machines, dishwashers, toilets, showerheads, some types of taps and urinals.

The scheme will also set minimum water efficiency standards for toilets and introduce voluntary labels on flow control devices.